Eyewear is commonly worn for a variety of reasons. As a result, a variety of eyewear types, each specifically designed and intended for a particular use or a particular environment has been developed. For example, sunglasses are often worn to protect a wearer's eyes from undesirably bright direct sun light. In such an environment, the undesirable light typically comes from above the user. Sunglasses also may be worn for protection in environments, such as around snow or water, where an uncomfortable amount of glare is present. In the instance of glare, the undesirable light often comes from below the user. For this reason, a lens having characteristics that are well suited for protecting a wearer's eyes from direct sun light, may be less effective at protecting a wearer's eyes from glare. As a result, a variety of eyewear lenses, having different characteristics and providing different advantages, have been developed. To gain the advantages of various types of lenses has, in the past, required a wearer to have multiple articles of eyewear--each having lenses of one of the various types.
Eyewear is also worn as a fashion accessory. For many wearers the color or tint of the eyewear may be an important factor in determining the suitability of the eyewear as an accessory. Moreover, the desired color or tint may vary depending on the circumstances and the items with which the wearer desires to coordinate. Again, wearers, in the past, were required to have different articles of eyewear in order to provide a selection of lenses having different colors or tints to coordinate with different fashions.
Accordingly, it would be advantageous if the lenses in an article of eyewear could be changed to allow the same eyewear to be used in different situations. For interchangeable lenses to be widely accepted, users must be able to remove and replace lenses quickly and easily.
However, eyewear lenses are typically mounted in a manner that prevents them from being quickly and easily removed from the frame. For example, in one type of eyewear, the portion of the frame that defines the lens opening is provided with a small gap. The gap is spanned by a threaded screw which can be tightened to decrease the size of the gap and, hence, the size of the lens opening. The lens is positioned within the lens opening and the screw is tightened to clamp the lens within the opening. In eyewear of this type, removal of the lens requires tools and is not typically performed by the wearer. Typically, removal also requires direct contact with the front and rear faces of the lens and, as a result, may scratch, dirty or mar the lens.
In some eyewear, the internal perimeter of the lens opening is provided with a groove into which the edge of the lens is engaged. In some eyewear of this type, the edge of the lens is received within the groove. Alternatively, the perimeter of the lens may have a raised rib which is received within the groove. Again, however, in this type of eyewear the lenses are not intended to be removed by a user.
In other eyewear, the frame is provided with a metal rim so that lenses having magnets about their periphery may be removably attached. Although this system allows a wearer to remove and interchange lenses, the presence of magnets on the lens may detract from the quality and appearance of the lens. Such a system also does not provide a sure mechanical connection of the lens to the frame. Moreover, such a system is not designed to reduce the possibility of a wearer handling the faces of the lens during the process of removing or interchanging the lenses. This increases the possibility of the front and rear faces of the lens being dirtied or damaged.
Clip-on lens covers are also available for eyewear. Such covers often include a tinted lens cover and are suited to be clipped onto prescription eyewear to convert them into prescription sunglasses. In many cases, the clip-on lens cover can be flipped up so that the wearer looks through the untinted prescription lenses or, alternatively, flipped down so that the wearer looks through both the prescription lenses and the tinted lens covers.